The presence of influenza here kicked up a notch this week, moving from “regional” to “widespread” according to the federal flu code used by the Maine Center for Disease Control and Prevention.

That designation reflects the confirmed presence of influenza in every part of the state, said Dr. Stephen Sears, state epidemiologist and acting director of the Maine CDC.

“It is not too late for people to get a flu vaccine,” Sears said in a recent interview. It takes only a few days for full immunity to develop, he said, and since flu season typically peaks in February and extends well into March, there is plenty of time for Mainers to protect themselves against the potentially life-threatening virus.

Story continues below advertisement.

Last year, the H1N1 “swine” flu scare raised public awareness as well as demand for vaccines against both that strain and the regular seasonal flu. The H1N1 flu turned out to be much less virulent than public health experts anticipated. This year, a similar H1N1 strain is incorporated into the widely available annual vaccine.

Sears said there have been only a handful of flu-related hospitalizations in Maine so far this year, and no flu-related deaths. That could mean the strains circulating in the U.S. are causing relatively mild symptoms in most people.

But generally, influenza is not accorded the respect it deserves.

Each year, millions of Americans are sickened by the respiratory virus, with dismal symptoms that include fever, muscle and joint pain and respiratory symptoms such as coughs and sore throats. It can take up to a week for a case of flu to run its course, meaning the loss of many hours of productive school and work time in addition to the general misery the illness causes.

About 200,000 Americans are hospitalized each year with influenza, and an estimated 35,000 die of flu-related conditions.

At highest risk for severe illness and death are very young children, the elderly, pregnant women and anyone with a compromised immune system due to HIV-AIDS, heart disease, lung disease, diabetes and other chronic conditions. Cancer treatment, including chemotherapy and radiation, also can weaken the immune system and open the door for influenza.

The United States Centers for Disease Control and Prevention recommend that everyone over the age of 6 months get a flu vaccine.

“Our major concern is for these most vulnerable populations,” Sears said.

Residential settings such as nursing homes are especially at risk for developing outbreaks among both residents and staff, he said: Already, three long-term care facilities in southern and western Maine have been hit by flu outbreaks. Schools, too, can be affected when the virus gets a foothold in students, teachers and staff, Sears said, although so far no schools in Maine are reporting widespread illness.

Sears said the state is working with hospitals, nursing homes and other health care providers to encourage all direct-care workers to get the flu vaccine in order to protect vulnerable patients. Teachers and child care workers also should be vaccinated, he said.

At Miller Drug on State Street in Bangor, pharmacist David Ingalls said this year’s flu season so far has been “lackluster” compared to last year.

“We are seeing a very mild influenza season,” he said.

While Miller Drug and other pharmacies have ample supplies of flu vaccine, he said, there is relatively little demand. Most of those who have been vaccinated at Miller Drug have been elderly customers and those with chronic illnesses — people who realize they’re at higher risk should they be exposed to the 2011 flu virus.

Flu vaccine is reformulated every year and typically contains three strains of influenza chosen from those emerging in the Southern Hemisphere during the spring and summer. This year’s formulation appears to be a good match for the strains that are sickening people in the United States, according to the U.S. CDC.

Flu vaccines are available at most health care provider offices as well as at most pharmacies. An online vaccine finder is available at the Health tab of the Bangor Daily News.